Low density pet litters and methods of making such pet litters

ABSTRACT

Compacting expanded perlite fines in the presence of a clay and water, followed by drying, produces particles with low density, good integrity, and surprisingly higher absorption by volume than non-compacted expanded perlite or non-swelling clay. Furthermore, addition of a clumping agent to the compacted granules results in a clumping litter with low density, good integrity and comparable clumping ability to traditional clay clumping litter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/245,349 filed Oct. 23, 2015, the disclosure of which is incorporatedby references in its entirety.

FIELD OF THE INVENTION

The present disclosure relates generally to a low density absorbentmaterial which can be used in both clumping and non-clumping pet litter.More specifically, the present disclosure is directed to low density petlitters comprising compacted particles of expanded perlite and clay, andmethods for making and using such pet litters.

BACKGROUND

Litter boxes are used by pets such as cats for elimination of urine andfecal matter. A litter box contains a layer of pet litter that receivesthe urine and fecal matter. The pet litter is granular, absorbent andeither non-clumping or clumping. A clumping pet litter is a litterproduct in which the particles facilitate formation of clumps after theurine and fecal matter is deposited in the pet litter. The clumps aretypically sifted from the litter box using a litter scoop and thendiscarded. Non-clumping pet litter is typically better at absorbingurine and thus removing urine odors, but replacing soiled non-clumpingpet litter without emptying the entire box of litter can be difficult.

Consumers fill their litter boxes based on volume, so litters should behighly absorbent by volume. However, traditional absorbent litters arebulky and dense, and thus packages of such litters are heavy anddifficult to handle.

Existing litters include compositions made from clay minerals, silicagel, and agricultural wastes. Clay minerals are absorptive but alsoheavy. Silica gel is also absorptive, but the commonly used aggregateshape and size can have poor cat acceptance, which can lead to housesoiling and/or a risk of urinary minerals aggregating into stones orcrystallizing in a cat. Agricultural wastes are also absorptive, butmany are in pellet form and can have poor animal acceptance.Agricultural waste litters, due to their composition, may also serve asfood source and thus support growth of odor causing microorganisms inthe litter box.

U.S. Pat. No. 5,655,480 to Steckel et al. discloses an animal controllitter comprised of a clumping agent, a surfactant, an odor controlagent and light weight aggregate expanded to form porous surfaces bysubjecting the aggregate to a temperature of 1,800° F. This litter has adensity between 5 and 10 lb/ft³. However, the material is lessabsorptive by volume than clay. Additionally, the expanded perliteaggregate material is fragile and can break down easily. The materialmay also be “too light” for good cat acceptance.

SUMMARY

The present disclosure relates to low density pet litters comprisingcompacted particles having a clay and expanded perlite fines. Thecompacted particles, in some embodiments, have expanded perlite fines ofa diameter smaller than 30 mesh (that is, having a diameter smaller than595 microns). As a non-limiting example, about 95% or more of theexpanded perlite fines in the compacted particles can be smaller than 30mesh (that is, having a diameter smaller than 595 microns) and nogreater than about 5% of the expanded perlite fines in the compactedparticles can have a diameter greater than 4 mesh (that is, a diametergreater than 4.76 mm).

The present inventors unexpectedly found that compacting expandedperlite fines in the presence of a clay and water, followed by drying,produces particles with low density, good integrity, and surprisinglyhigher absorption by volume than non-compacted expanded perlite or theclay. The compacted granules results in a clumping litter with lowdensity, good integrity and comparable clumping ability to traditionalclay clumping litter.

Accordingly, in a general embodiment, the present disclosure provides amethod of making a pet litter. The method comprises: compacting amaterial comprising a clay and expanded perlite fines to form acompacted material comprising expanded perlite fines; breaking thecompacted material comprising expanded perlite fines to form particlesof the compacted material comprising expanded perlite fines; separatingthe particles which have a size within a predetermined size range from aremainder of the particles; drying the particles which have the sizewithin the predetermined size range; and using the dried particles as atleast a portion of the pet litter. In another embodiment, the presentdisclosure provides a pet litter made by this method.

In one embodiment, the breaking of the compacted material comprisingexpanded perlite fines and/or drying are optional.

In an embodiment, the expanded perlite fines have a size not greaterthan about 600 microns. In one embodiment, the expanded perlite fineshave a diameter from about 50 microns to about 600 microns,alternatively from about 100 microns to about 550 microns, alternativelyfrom about 150 microns to about 500 microns, alternatively from about200 microns to about 450 microns, alternatively from about 250 micronsto about 400 microns, alternatively from about 300 microns to about 350microns.

In an embodiment, the compacting is performed at a pressure from about500 psi (3447 kPa) to about 1,300 psi (8963.18 kPa).

In an embodiment, the material comprises about 20 wt % to about 85 wt %of the clay. The clay can be (i) a swelling clay, (ii) a non-swellingclay, or (iii) a mixture of a swelling and a non-swelling clay. At leasta portion of the clay can be added to the expanded perlite fines as adry mix before the compacting of the material. At least a portion of theclay can be pre-blended with water and then added to the expandedperlite fines before the compacting of the material.

In an embodiment, the water in the material comprises about 5.0 wt % toabout 10.0 wt % of water.

In an embodiment, the material comprises about 5 wt % to about 95 wt %,alternatively about 5 wt % to about 85 wt %, alternatively about 5 wt %to about 75 wt %, alternatively about 5 wt % to about 65 wt %,alternatively about 5 wt % to about 55 wt %, alternatively about 5 wt %to about 45 wt %, alternatively about 5 wt % to about 35 wt %,alternatively about 5 wt % to about 25 wt %, or alternatively about 5 wt% to about 15 wt % of the expanded perlite fines.

In an embodiment, the predetermined size range is about 595 microns toabout 2,380 microns.

In an embodiment, the particles are dried to a moisture content of about0.25 wt % to about 10.0 wt %.

In another embodiment, the present disclosure provides a pet littercomprising dried particles of compacted material comprising a clay andexpanded perlite fines, the particles having a density of about 25.0lb/ft³ to about 55.0 lb/ft³, alternatively about 30.0 lb/ft³ to about53.0 lb/ft³, or alternatively about 40.0 lb/ft³ to about 50.0 lb/ft³.

In an embodiment, the litter is a non-clumping litter that does notcontain a clumping agent.

In an embodiment, the litter is a clumping litter comprising a clumpingagent. The clumping agent can be selected from the group consisting ofbentonite, guar gum, starches, xanthan gum, gum Arabic, gum acacia,silica gel, and mixtures thereof.

In an embodiment, the pet litter further comprises an additive selectedfrom the group consisting of an odor control agent, a fragrance, ananti-microbial agent, an anti-sticking agent, an agent for controllingpH, a dye, a coloring agent, a de-dusting agent, a disinfectant, andcombinations thereof. An odor control agent can be carbon, particularlyactivated carbon.

In another embodiment, the present disclosure provides a method ofmanaging animal waste. The method comprises using pet litter comprisingdried particles of compacted material comprising expanded perlite, theparticles having a density of about 25.0 lb/ft³ to about 55.0 lb/ft³,alternatively about 30.0 lb/ft³ to about 53.0 lb/ft³, or alternativelyabout 40.0 lb/ft³ to about 50.0 lb/ft³.

In another embodiment, the present disclosure provides a method oftreating out-of-box elimination of a pet. The method comprises using petlitter comprising dried particles of compacted material comprisingexpanded perlite, the particles having a density of about 25.0 lb/ft³ toabout 55.0 lb/ft³, alternatively about 30.0 lb/ft³ to about 53.0 lb/ft³,or alternatively about 40.0 lb/ft³ to about 50.0 lb/ft³ in a litter boxlocated in a building in which the pet resides.

In another embodiment, the present disclosure provides a method oftreating, preventing or reducing the risk of a lower urinary tractdisease in a cat. The method comprises using pet litter comprising driedparticles of compacted material comprising expanded perlite, theparticles having a density of about 25.0 lb/ft³ to about 55.0 lb/ft³,alternatively about 30.0 lb/ft³ to about 53.0 lb/ft³, or alternativelyabout 40.0 lb/ft³ to about 50.0 lb/ft³ in a litter box located in abuilding in which the cat resides.

An advantage of one or more embodiments provided by the presentdisclosure is to provide improved pet litters.

Another advantage of the present disclosure is to provide methods ofmaking improved pet litters.

A further advantage of the present disclosure is to provide pet littersthat have a low density without sacrificing particle integrity orabsorptive performance.

Still another advantage of the present disclosure is to provide petlitters that have both a low density and good pet acceptance.

Yet another advantage of the present disclosure is to enable lighterpackages of pet litter without decreasing the volume thereof.

Another advantage of the present disclosure is to enable a pet owner tomore easily purchase, transport and utilize a package of pet litter.

A further advantage of the present disclosure is to provide a lowdensity granular absorbent with good particle integrity and havingsurprisingly improved absorption relative to traditional clay litter andthe pre-processed principal raw material.

Still another advantage of the present disclosure is to provide amaterial that can be used as an improved non-clumping pet litter oremployed in a formulation for an improved clumping pet litter.

Additional features and advantages are described herein and will beapparent from the following Detailed Description.

DETAILED DESCRIPTION

As used in this disclosure and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a material” or “thematerial” includes two or more materials.

The words “comprise,” “comprises” and “comprising” are to be interpretedinclusively rather than exclusively. Likewise, the terms “include,”“including” and “or” should all be construed to be inclusive, unlesssuch a construction is clearly prohibited from the context.

However, the devices and compositions disclosed herein may lack anyelement that is not specifically disclosed. Thus, a disclosure of anembodiment using the term “comprising” includes a disclosure ofembodiments “consisting essentially of” and “consisting of” thecomponents identified. Similarly, the methods disclosed herein may lackany step that is not specifically disclosed herein. Thus, a disclosureof an embodiment using the term “comprising” includes a disclosure ofembodiments “consisting essentially of” and “consisting of” the stepsidentified. “Consisting essentially of” means that the embodimentcomprises more than 50% of the identified components, or at least 75% ofthe identified components, or at least 85% of the identified components,or at least 95% of the identified components, for example at least 99%of the identified components.

The term “and/or” used in the context of “X and/or Y” should beinterpreted as “X,” or “Y,” or “X and Y.” Where used herein, the terms“example” and “such as,” particularly when followed by a listing ofterms, are merely exemplary and illustrative and should not be deemed tobe exclusive or comprehensive. Any embodiment disclosed herein can becombined with any other embodiment disclosed herein unless explicitlystated otherwise.

All percentages expressed herein are by weight of the total weight ofthe composition unless expressed otherwise. As used herein, “about” and“approximately” are understood to refer to numbers in a range ofnumerals, for example the range of −10% to +10% of the referencednumber, or within −5% to +5% of the referenced number, or within −1% to+1% of the referenced number, or within −0.1% to +0.1% of the referencednumber. All numerical ranges herein should be understood to include allintegers, whole or fractions, within the range. Moreover, thesenumerical ranges should be construed as providing support for a claimdirected to any number or subset of numbers in that range. For example,a disclosure of from 1 to 10 should be construed as supporting a rangeof from 1 to 8, from 3 to 7, from 1 to 9, from 3.6 to 4.6, from 3.5 to9.9, and so forth.

Numerical adjectives, such as “first” and “second,” are merely used todistinguish components. These numerical adjectives do not imply thepresence of other components, a relative positioning, or anychronological implementation. In this regard, the presence of a “secondwidget” does not imply that a “first widget” is necessarily present.Further in this regard, a “second widget” can be used before, after, orsimultaneously with any “first widget.”

The terms “pet” and “animal” are used synonymously herein and mean anyanimal which can use a litter box, non-limiting examples of whichinclude a cat, a dog, a rat, a ferret, a hamster, a rabbit, an iguana, apig or a bird. The pet can be any suitable animal, and the presentdisclosure is not limited to a specific pet animal. The term“elimination” means urination and/or defecation by a pet.

As used herein, the term “litter” means any substance that can absorbanimal urine and/or decrease odor from animal urine and/or feces. A“clumping litter” forms aggregates in the presence of moisture, theaggregates distinct from the other litter in the litter box. A“non-clumping litter” does not form distinct aggregates.

The term “litter box” means any apparatus that can hold pet litter, forexample a container with a bottom wall and one or more side walls,and/or any apparatus configured for litter to be positioned thereon, forexample a mat or a grate. As a non-limiting example, a litter box may bea rectangular box having side walls that have a height of at least aboutsix inches.

The term “mesh” is defined by the ASTM E-11 U.S.A. standardspecification for sieves. As used herein, “size” of a particle refers tothe length of the longest dimension of the particle.

The methods and devices and other advances disclosed herein are notlimited to particular methodologies, protocols, and reagents because, asthe skilled artisan will appreciate, they may vary. Further, theterminology used herein is for the purpose of describing particularembodiments only and does not limit the scope of that which is disclosedor claimed.

Unless defined otherwise, all technical and scientific terms, terms ofart, and acronyms used herein have the meanings commonly understood byone of ordinary skill in the art in the field(s) of the presentdisclosure or in the field(s) where the term is used. Although anycompositions, methods, articles of manufacture, or other means ormaterials similar or equivalent to those described herein can be used,the preferred devices, methods, articles of manufacture, or other meansor materials are described herein.

An aspect of the present disclosure is a method of making a pet litter.The method can comprise compacting a material comprising expandedperlite fines, a clay and water, for example using compacting rolls.

The compacting can be performed at a compaction roll back-pressure of atleast about 500 psi (3447 kPa), for example about 500 psi (3447 kPa) toabout 1,300 psi (8963.18 kPa), such as about 500 psi (3447 kPa) to about800 psi (5516 kPa) or about 800 psi (5516 kPa) to about 1,300 psi(8963.18 kPa). The size of the expanded perlite fines is not greaterthan about 30 mesh (that is, a diameter not greater than 595 microns).As a non-limiting example, about 95% or more of the expanded perlitefines in the compacted particles can have a diameter smaller than 30mesh (that is, a diameter smaller than 595 microns) and no greater thanabout 5% of the compacted particles can have a diameter greater than 4mesh (that is, a diameter greater than 4.76 mm). In an embodiment, theexpanded perlite fines comprise particles eliminated in step 101 of themethod 100 disclosed in U.S. Patent App. Pub. No. 2014/0174370 to Hucket al., herein incorporated by reference in its entirety.

The present disclosure is not limited to a specific means of forming thecompacted particles, and other means of compaction or agglomeration ofthe perlite fines can be employed additionally or alternatively tocompacting rolls. These other means include, for example, tumble/growthagglomeration; low-, medium-, or high pressure agglomeration; punch anddie; roller press; high shear mixer granulator; extrusion; andcombinations thereof.

Perlite is a generic term for a naturally occurring siliceous rock. Onefeature which sets perlite apart from other volcanic glasses is thatwhen heated to a suitable point in its softening range, perlite expandsfrom four to twenty times the original volume. This expansion is due, atleast in part, to the presence of two to six percent combined water inthe crude perlite rock. Firing, i.e., quickly heating to above 1,600° F.(871° C.), causes the crude rock to pop in a manner similar to popcornyielding a very open, highly porous structure referred to as expandedperlite.

In an embodiment, the amount of expanded perlite fines is about 5 wt %to about 15 wt % of the material, alternatively about 7 wt % to about 10wt %, or alternatively about 8 wt % to about 9.5 wt % of the material.In an embodiment, the amount of the water is about 5 wt % to about 10 wt% of the material, alternatively about 6 wt % to about 9 wt %,alternatively about 6.5 wt % to about 8 wt % of the material.

In an embodiment, the amount of the clay is about 20 wt % to about 85.0wt % of the material, alternatively about 30.0 wt % to about 70.0 wt %,alternatively about 40.0 wt % to about 60.0 wt % of the material. Theclay can be swelling or non-swelling. The clay comprises one or moreclay minerals selected from the group consisting of bentonite, kaolin,smectite, illite, chlorite, sepiolite, atapulgite, montmorillonitesmectite, calcium montmorillonite, and sodium montmorillonite. In oneembodiment, the clay is a mixture of a swelling and a non-swelling clay,wherein the swelling clay is sodium bentonite and the non-swelling clayis calcium montmorillonite. In an embodiment, the swelling claycomprises about 20 wt % to about 40.0 wt %, alternatively about 25.0 wt% to about 35.0 wt % of the material, and the non-swelling claycomprises about 50.0 wt % to about 70.0 wt %, alternatively about 60.0wt % to about 70.0 wt % of the material.

At least a portion of the clay can be added to the expanded perlitefines as a dry mix before the compacting. Alternatively or additionally,at least a portion of the clay can be pre-blended with at least aportion of the water and then added to the expanded perlite fines beforethe compacting.

In an embodiment, the compacting forms a compacted material such assheets and/or briquettes of compacted expanded perlite fines. However,the compacted material is not limited to a specific shape, size or form.Furthermore, as noted above, the present disclosure is not limited to aspecific means of compaction or agglomeration of the clay and perlitefines to form the compacted material. For example, the compactedmaterial can be in the form of a pellet (e.g., a flattened pellet), atablet or a puck.

Then the compacted material can be ground and/or crushed, for example bya milling system or any other suitable apparatus known to one skilled inthe art, to obtain particles of compacted material comprising clay andexpanded perlite fines. One or more sieves can be used to obtain theparticles of compacted material comprising clay and expanded perlitefines that have a desired size by separating the particles having thedesired size from the remainder of the particles. The desired particlesize is from about 30 mesh (595 microns) to about 8 mesh (2,380microns). The particles of compacted material comprising clay andexpanded perlite fines are not evenly distributed within the size range.Commercially available shaker screens may be utilized.

The particles of compacted material comprising clay and expanded perlitefines that have the desired size can be subjected to drying to removemoisture from the particles without substantially damaging theparticles. For example, the particles can be transferred to a dryer suchas a fluidized bed dryer. The resultant moisture level can be about0.25% to about 10%, for example about 2%.

The dried particles of compacted material comprising clay and expandedperlite fines have a density of about 25.0 lb/ft³ to about 55.0 lb/ft³,alternatively about 30.0 lb/ft³ to about 53.0 lb/ft³, or alternativelyabout 40.0 lb/ft³ to about 50.0 lb/ft³.

In some embodiments, the dried particles of compacted materialcomprising clay and expanded perlite fines are combined with a clumpingagent; i.e., an agent that binds adjacent particles when wetted. Thecombination of the dried particles with the clumping agent can beperformed in a mixer and can form at least a portion of a clumping petlitter. The clumping litter comprises the dried compacted particles andthe clumping agent in a ratio from 99:1 to 94:6, for example about 96:4.Non-limiting examples of suitable clumping agents include bentonite(such as sodium bentonite), guar gum, starches, xanthan gum, gum Arabic,gum acacia, silica gel, other minerals, and mixtures thereof. Apreferred embodiment of the clumping agent comprises guar gum. In anembodiment, starch is used in the clumping agent, and is added to theparticles of compacted perlite fines, for example, after drying.

In other embodiments, the dried particles of compacted materialcomprising clay and expanded perlite fines are not coated with aclumping agent, and the dried particles of compacted material comprisingexpanded perlite form at least a portion of a non-clumping litter. Insuch embodiments, the dried particles can be packaged directly after thedrying without further processing.

Various additives may be optionally applied to the dried compactedparticles. Non-limiting examples of suitable additives include an odorcontrol agent, a fragrance, an anti-microbial agent, an anti-stickingagent, an agent for controlling pH, a dye, a coloring agent, ade-dusting agent, a disinfectant, and combinations thereof. In anembodiment, at least a portion of the dried compacted particles arecoated with a colorant.

For embodiments in which the pet litter is a non-clumping litter, theadditives can be applied to the dried compacted particles directly afterthe drying, to form the non-clumping litter, without further processing.Then the non-clumping litter can be packaged directly after theapplication of the additives, without further processing.

For embodiments in which the pet litter is a clumping litter, theadditives and the clumping agent, together or separately, can becombined with the dried compacted particles directly after the drying,to form the clumping litter, without further processing. Then theclumping litter can be packaged directly after the combination, withoutfurther processing.

In a preferred embodiment, the pet litter does not contain clay. In apreferred embodiment, the pet litter does not contain agriculturalproducts, such as alfalfa, corn, corn stalk, corn flour, oat hull, oatstalk, oat flour, barley hull, barley meal, barley stalk, barley flour,wheat hull, wheat straw, wheat flour, soybean hull, soybean meal,soybean floor, rye hull, rye meal, rye straw, rye flour, rice straw,rice hull, sorghum straw, sorghum hull, sunflower seeds, bamboo,lemongrass, switchgrass, catnip, oregano, parsley, rosemary, sage,thyme, valerian root, alyssum, chrysanthemum, honeysuckle, hops,lavender, apples, berries, orange peels, orange pulp, sunflower hulls,coffee, tea, sawdust, paper, cellulose, corncob, corn kernel, DistillersDried Grain (DDG), corn pellet, oaf pellet, barley pellet, wheatmiddlings, soybean pellet, rye pellet, rice grain, rice pellet, sorghumgrain, sorghum pellet, sunflower seed, almond, pistachio, walnut, pecan,hazelnut, peanut, acorn, wheat middlings, wheat straws, or combinationsthereof.

Another aspect of the present disclosure is a pet litter comprisingdried particles of compacted material comprising clay and expandedperlite fines, the dried particles having a density of about 25.0 lb/ft³to about 55.0 lb/ft³, alternatively about 30.0 lb/ft³ to about 53.0lb/ft³, or alternatively about 40.0 lb/ft³ to about 50.0 lb/ft³. Yetanother aspect of the present disclosure is a pet litter made by any ofthe methods disclosed herein.

Another aspect of the present disclosure is a sealed package at leastpartially enclosing any of the embodiments of the pet litter disclosedherein, for example a sealed box or a sealed bag containing such petlitter. A further aspect of the present disclosure is a method of usinga pet litter, the method comprising positioning at least a portion of apet litter contained by a package into a litter box. The method canmanage animal waste, such as cat urine; prevent or treat cat out-of-boxelimination; or treat or prevent lower urinary tract diseases in a cat,such as urinary plugs, struvite or oxalite stones, idiopathic cystitis,or renal reflux. In an embodiment, one or more of the pet littersdisclosed herein are used to treat a cat having an out-of-boxelimination issue. As used herein, a cat that has “an out-of-boxelimination issue” is a cat that has eliminated outside of the litterbox at least once in the last month, and in an embodiment eliminatedoutside of the litter box at least once in the last week.

EXAMPLES

The following non-limiting examples are illustrative of embodiments ofthe pet litters provided by the present disclosure and advantagesthereof.

Example 1: Clumping Litter Production—1

Absorbent granules were produced using a compaction process.

-   -   1. Swelling clay (sodium bentonite), non-swelling clay (calcium        montmorillonite), and water were blended and then fed into a set        of compacting rolls (Table 1).    -   2. The compaction rolls, having roll back-pressure force        set-point of 800 psi, formed the in-feed into pellets.    -   3. The pellets were then crushed and sized to −8/+30 mesh.    -   4. The screened material was then dried to a moisture content of        approx. 2%.    -   5. After drying, the granular absorbent material was evaluated        for density, absorption, and particle integrity (attrition).

Example 2: Clumping Litter Production—2

Absorbent granules were produced using a compaction process.

-   -   1. Swelling clay (sodium bentonite), non-swelling clay (calcium        montmorillonite), expanded perlite fines, and water were blended        and then fed into a set of compacting rolls (Table 1).    -   2. The compaction rolls, having roll back-pressure force        set-point of 800 psi, formed the in-feed into pellets.    -   3. The pellets were then crushed and sized to −8/+30 mesh.    -   4. The screened material was then dried to a moisture content of        approx. 2%.    -   5. After drying, the granular absorbent material was evaluated        for density, absorption, and particle integrity (attrition).

TABLE 1 Litter Formulation (pre-dried) Example 1 Example 2 Ingredient(in wt %) (in wt %) Swelling Clay 32.5% 23.3% (sodium bentonite)Non-Swelling Clay 60.5% 60.5% (calcium montmorillonite) Perlite Fines 9.3% Water  7.0%

Example 4: Bulk Density Measurement

The bulk density of the absorbent granules from Example 1 was measuredusing a filling hopper (800 284-5779 Seedburo®; part number 151 FillingHopper complete with 64P Pan), stand, and pint sized (550.06 cm³ dryvolume) sample cup according to the procedure below:

-   -   1. The litter was poured into the filling hopper until it was        full.    -   2. Next, the empty pint cup was placed on a balance and the        balance was zeroed.    -   3. The cup was then placed beneath the filling hopper. The        distance between the filling hopper discharge, and the top edge        of the cup was set at 2 inches.    -   4. The filling hopper discharge slide was then opened to allow        product to fall into the empty sample cup. Litter was allowed to        flow until the cup was full, and then for an additional 1 to 2        seconds of overflow.    -   5. A straight edge was then used to remove excess product from        the top of the cup; leveling the cup contents with the rim of        the cup.    -   6. The cup with litter was then returned to the balance and the        weight of the litter recorded.    -   7. Steps 1-6 were repeated three times.    -   8. Mass value was converted to pounds per cubic foot (lb/ft³)        using the conversion factor 1 gram per cubic centimeter (gm/cm³)        equals 62.4269 lb/ft³ (1 gram per dry pint (g/dry-pt) equals        0.113358 lb/ft³).

The average bulk density and standard deviation were calculated andreported in Table 2. As shown in Table 2, the tested pet litter wassignificantly less dense than the clay litter benchmarks.

Example 5: Absorption by Volume Measurement

The absorption by volume of the litter from Example 1 was measured usinga bulk density apparatus (800 284-5779 Seedburo®; part number 151Filling Hopper complete with 64P Pan); a straight-edge such as a 12 inchruler; a funnel; a ring support (4″) and support stand (24″); agraduated cylinder (at least 250 ml); an interval timer; and a specimencup with a known volume (150 ml) according to the procedure below.

-   -   1. A representative portion of sample was used to fill about ¾        of the hopper of the bulk density apparatus.    -   2. A tared specimen cup was placed under the center of the        hopper approx. 2¾ inches below the gate opening. The hopper gate        was opened quickly and the sample allowed to fill the cup and        overflow into the pan below.    -   3. The sample was leveled to the top edge of the specimen cup        using a straight edge and sawing motion. The volume of the        sample was now assumed to be equivalent to the volume of the        specimen cup.    -   4. The sample was then transferred to the sorption funnel. The        sorption funnel was positioned above the graduated cylinder        using the ring support and stand so that the clamped hose end        extended ½″ to 1″ into the cylinder.    -   5. Using the graduated cylinder as a measure and transfer        vessel, 250 ml of cold tap water (V_(initial)) was added to the        sorption funnel.    -   6. After a 10 minute soak time, the 250 ml graduated cylinder        was placed under the funnel drain hose and the hose clamp        released.    -   7. Water from the funnel was allowed to drain into the graduated        cylinder for 5 minutes.    -   8. Using fingers, the hose was squeezed to release any water        trapped therein.    -   9. The graduated cylinder was examined, and the total volume of        water drained from the recorded (V_(final)).

Calculation of Percentage Absorption by Volume:

Volume of water absorbed (ml)=V _(initial) (initial water volume)−V_(final) (final water volume)

% Absorption by volume=(Volume of water absorbed (ml)/Volume of specimencup (ml))×100

Example 6: Particle Integrity (Attrition) Measurement

The attrition of the absorbent material from Example 1 was measuredaccording to the procedure below:

-   -   1. A representative sample of between 150 mL and 300 mL was        collected and hand sieved on a 8″ diameter 30 mesh sieve. Any        particles that passed through were discarded, and any that        remained on the screen or stuck in the screen were brushed out        and kept for further analysis.    -   2. The sample was then poured into the bulk density hopper        (Seedburo®; part number 151 Filling Hopper) and released into a        tared % cup measuring cup (60 mL). A straight edge was used to        strike off the excess material from the measuring cup.    -   3. The tared measuring cup with the material was then placed on        the scale to find the original mass of the sample, MO.    -   4. The weighed sample was poured onto a 40 mesh sieve, and this        screen placed on top of a catch pan. The stack was then loaded        into a Rotap (RX-29) and shaken with the arm engaged for 4        minutes.    -   5. After shaking on the Rotap, the material in the pan was        discarded, and the material on the screen and the material stuck        in the 40 mesh screen were collected and weighed to find the        final mass of the sample, MR.

Calculation of Attrition %

Attrition %=((MO−MR)/MO)×100

The results of attrition testing were recorded and are reported in Table2. Referring to Table 2, the particle integrity of the tested pet litteris good (<5.0%).

Example 7: Clump Integrity Measurement

The material from Example 7 was tested for clump performance accordingto the following procedure:

-   -   1. An 8″ diameter sieve with ¾″ mesh was stacked on top of a        sieve pan and placed on the bottom of a support stand.    -   2. A trap door assembly was attached to the support stand and        positioned ten inches above ¾″ sieve.    -   3. A representative sample of the litter from Example 5 was        added to a litter testing pan. The depth of material was three        inches.    -   4. A self-leveling 25 ml burette was positioned on a support        stand three inches above the litter surface. This setup was used        to dispense 25 ml aliquots of feline urine liquid to the litter        surface, forming a clump in the litter. This process was        repeated in a variety of location of the litter pan until the        desired number of clumps was created (in this case 20 clumps).    -   5. At the end of the desired time interval (15 min or 24 hr),        the clump was removed from the litter, and its mass recorded as        W1.    -   6. The clump was then centered on the trap door mechanism        assembled in step 2.    -   7. Next the lever was actuated to release the trap door,        allowing the clump to fall onto the ¾″ test sieve.    -   8. The clump was carefully removed from the screen in a manner        which allowed loose material to fall free of the clump, but not        in a manner which caused additional damage to the clump. If the        clump broke into pieces, largest piece retained on the ¾″ screen        was selected. If nothing is retained on the screen, the result        is zero (0) weight.    -   9. The clump or largest piece was weighed and the mass recorded        as W2.    -   10. The Percentage of Cohesion value was calculated using the        following formula:

% Cohesion=(W2(final weight)/W1(initial weight))×100

The Percentage of Cohesion values for all clumps were averaged, and theresults recorded in Table 2. As shown in Table 2, the Percentage ofCohesion values for the tested pet litter were comparable to that of thecurrent clay litter.

TABLE 2 Summary of Testing Results Clump Clump Bulk Cohesion CohesionMaterial Density Attrition 15 min. 24 Hours Class Sample (lb/ft³) (%)(%) (%) Raw bentonite 69.0 95.8 Material granules Clumping Example 149.1 13.6 90.6 92.9 Litter Clumping Example 2 51.5 4.9 93.6 90.1 Litter

CONCLUSIONS

The results show that the tested pet litter is a low density granularabsorbent with good particle integrity and has surprisingly improvedabsorption relative to traditional clay litter and the pre-processedprincipal raw material. Specifically, the density is reduced relative tobentonite granule litters (Table 2). The particle integrity is good(<5.0%). Specifically, attrition (integrity) of Example 2 is better thanExample 1 which was a surprising result because perlite and perlitefiles are not known to be binders. The perlite fines gave strength tothe granules. That is, it was surprisingly found that granules withperlite fines have reduced density and greater particle integrity whileat the same time maintain comparable clumping compared to bentonitegranule clay litter benchmark as well as intact granules of withoutexpanded perlite fines (Table 2).

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A method of making a pet littercomprising: compacting a material comprising clay and expanded perlitefines to form a compacted material comprising expanded perlite fines;breaking the compacted material comprising expanded perlite fines toform particles of the compacted material comprising expanded perlitefines; separating the particles which have a size within a predeterminedsize range from a remainder of the particles; drying the particles whichhave the size within the predetermined size range; and using the driedparticles as at least a portion of the pet litter.
 2. The method ofclaim 1, wherein the expanded perlite fines have a size not greater thanabout 600 microns.
 3. The method of claim 1, wherein the compacting isperformed at a pressure from about 500 psi to about 1,300 psi.
 4. Themethod of claim 1, wherein the material comprises about 20 wt % to about85 wt % of the clay.
 5. The method of claim 4, wherein the clay isselected from the group consisting of (i) a swelling clay, (ii) anon-swelling clay, and (iii) a mixture of a swelling and a non-swellingclay.
 6. The method of claim 5, wherein at least a portion of the clayis added to the expanded perlite fines as a dry mix before thecompacting of the material.
 7. The method of claim 5, wherein at least aportion of the clay is pre-blended with water and then added to theexpanded perlite fines before the compacting of the material.
 8. Themethod of claim 1, wherein the material comprises about 5.0 wt % toabout 10.0 wt % of water.
 9. The method of claim 1, wherein the materialcomprises about 5 wt % to about 15 wt % of the expanded perlite fines.10. The method of claim 1, wherein the predetermined size range is about595 microns to about 2,380 microns.
 11. The method of claim 1, whereinthe particles are dried to a moisture content of about 0.25 wt % toabout 10.0 wt %.
 12. The method of claim 1, wherein breaking thecompacted material comprising expanded perlite fines or drying areoptional.
 13. A pet litter comprising dried particles of compactedmaterial comprising expanded perlite, the particles having a density ofabout 25.0 lb/ft³ to about 55.0 lb/ft³.
 14. The pet litter of claim 12,wherein the litter is a non-clumping litter that does not contain aclumping agent.
 15. The pet litter of claim 12, wherein the litter is aclumping litter comprising a clumping agent.
 16. The pet litter of claim14, wherein the clumping agent is selected from the group consisting ofbentonite, guar gum, starches, xanthan gum, gum Arabic, gum acacia,silica gel, and mixtures thereof.
 17. The pet litter of claim 12,further comprising an additive selected from the group consisting of anodor control agent, a fragrance, an anti-microbial agent, ananti-sticking agent, an agent for controlling pH, a dye, a coloringagent, a de-dusting agent, a disinfectant, and combinations thereof. 18.The pet litter of claim 17, wherein the odor control agent is activatedcarbon.
 19. A pet litter made by the method of claim
 1. 20. A method ofmanaging animal waste, the method comprising using pet litter comprisingdried particles of compacted material comprising expanded perlite, theparticles having a density of about 25.0 lb/ft³ to about 55.0 lb/ft³, ina litter box.
 21. A method of treating out-of-box elimination of a pet,the method comprising using pet litter comprising dried particles ofcompacted material comprising expanded perlite, the particles having adensity of about 25.0 lb/ft³ to about 55.0 lb/ft³, in a litter boxlocated in a building in which the pet resides.
 22. A method oftreating, preventing or reducing the risk of a lower urinary tractdisease in a cat, the method comprising using pet litter comprisingdried particles of compacted material comprising expanded perlite, theparticles having a density of about 25.0 lb/ft³ to about 55.0 lb/ft³, ina litter box located in a building in which the cat resides.